Cystic fibrosis (CF) is one of the most common autosomal recessive diseases of man, affecting 1 in 2500 Caucasian newborns. The disease primarily affects the lungs and pancreas, where damage results from the thick sticky mucus which accumulates and leads to obstruction and organ damage. The current average survival is about age 25, with death usually coming from respiratory failure. After years of work, the CF gene was cloned by our laboratory in collaboration with the Hospital for Sick Children in Toronto in 1989, using the "reverse genetics" strategy. The gene encodes a 1480 amino acid membrane protein, and the common mutation is a deletion of phenylalanine 508. We now propose a series of studies to further define the function and regulation of expression of the CF gene. This will include the identification of additional mutations responsible for CF by a variety of sensitive techniques, a study of the function of the gene by transfection into cystic fibrosis cells and assessment of correction of the defect, site-specific mutagenesis of various regions of the gene, the generation of antibodies to domains of the protein product in order to further characterize its expression, and a study of the regulation of transcription by defining the promoter sequences responsible for epithelial specificity. Furthermore, we have recently identified evidence for alternative splicing of the gene which is likely to have important functional consequences, and this phenomenon will be intensively investigated. These studies should bring us much closer to an understanding of the normal function of the CF gene, and should lay the groundwork for the development of effective therapies.